This invention relates to drive axles for large land vehicles, such as wheel loaders, of the type having drive components disposed within hubs at the outer ends of the axle and having fluid pressure actuated brakes which may be located within the hub, but not necessarily, and, more particularly, to a fluid system for providing fluid not only for actuation of the brakes but also for lubricant flow to the operating components of the axle assembly.
Prior art drive axle assemblies are illustrated in Keese U.S. Pat. No. 4,037,694 and Sidles, Jr. et al. U.S. Pat. No. 4,142,615. In each case, the outer end of the axle comprises a cavity containing a planetary gear drive assembly and a fluid actuated brake means for braking the drive shaft or sun gear relative to the spindle. In Chamberlain U.S. Pat. No. 4,140,198, the brake means is not in the planetary drive cavity but in an adjacent cavity. In each case, the brake means is actuated by hydraulic fluid which typically also is associated with the hydraulic system used for controlling the transmission. Lubrication of the drive components and cooling of the brakes are accomplished by maintaining a pool of lubricant in the cavity which in Keese is separated from the hydraulic actuating fluid but which may communicate with the differential housing although it is said that there is no significant flow to the housing while in Chamberlain there is intended communication. In one embodiment of Sidles, Jr. et al., hydraulic fluid is sealed in the cavity to lubricate and cool the brake pack and drive components. In any case, lubrication and cooling are entirely separate from the hydraulic brake actuating system.